Balanced draft space heater



March 1953 J. L. HEIMAN 3,082,758

BALANCED DRAFT SPACE HEATER Filed March 13, 1961 m T N E V N I JORDAN L. HEIMAN BY TTORNEY FIGS.

" atent 3,082,758 Patented Mar. 26, 1963 3,082,758 BALANCED DRAFT SPACE HEATER Jordan L. Heiman, 110 Stonyside, Olivette, Mo. Filed Mar. 13, 1961, Ser. No. 95,438 8 Claims. (Cl. 126-110) This invention is a continuation in part of patent application Serial No. 673,185, filed July 22, 1957, now abandoned, and relates to space heaters broadly, and more particularly of a type intended to be used in stores, shops, offices, homes, trailers and the like.

The invention has among its objects the production of such heaters that will be neat and attractive in appearance, simple in construction and maintenance, economical in operation, safe, sufliciently rugged and sturdy to render many years of service with a minimum amount of repairs and servicing, and which will be otherwise satisfactory and efiicient for use wherever deemed applicable.

One of the principal objects of my invention is to construct a mechanism of the kind described, in which there will be a substantially balanced draft system employed to thereby assure of approximately equal air pressures at the flue gas outlet and the combustion air intake.

Another object of the invention is to so construct said device that there is a minimum likelihood of back draft being created at the flue, and with a result maintenance of the required draft through the combustion chamber of the heater, and without flash-back, back-firings, etc. occurring.

Yet another object of my invention is to so construct the mechanism, that no matter what the wind effect is, the pressures created at the stack air intake and air discharge are equal to one another, thus maintaining a sub stantially constant pressure across the fuel burner so as to insure a steady and constant volume of air for combustion under all wind conditions and without the use of any barometric draft regulator or draft hood.

An added object of the invention is to so construct the parts of the heater and flue that the combustion chamber system is substantially semihermetically sealed, and thereby eliminate all possibility of escape or leakage or" the flue gases into the space that is to be heated.

A further object of my inventionis to so construct such a heater wherein the atmospheric air inlet that communicares with the fresh-air intake to the burner will be as close as possible to the vicinity of the flue-gas discharge into the atmosphere.

Many other objects and advantages of the construction herein shown and described, and the advantages and uses thereof, will be obvious to those skilled in the art to which this invention appertains, as will be more readily and clearly seen from the following description.

In the drawings, wherein like reference numeralsrepresent like or corresponding parts throughout the views,

FIGURE 1 is a front elevation of the heaten'with parts of the room structure in which it is installed, broken away;

FIGURE 2 is a vertical cross-sectional view of the same, taken substantially along the line 22 of FIG. 1; and

FIGURE 3 is a horizontal cross-sectional detail, taken substantially along the line 33 of FIG. 1.

FIGURE 4 is a modified form of flue structure for the heater.

Referring more particularly to the drawings, wherein I have illustrated a preferred embodiment of my invention, there is shown a space heater that is uniquely adapted for installations on the floor of a trailer or mobile home, although it may be used to heat other types of rooms as well, and in the form shown the hot air is discharged from the heater into an under-the-floor duct or plenum system for distribution to one or more points of outlet as desired.

There are inner and outer upright shells or casings 4 and 1, respectively, one within the other and transversely spaced apart, and the housing or casing or shell 1 may enclose the inner casing 4 and present an attractive and neat appearance in the room in Which the heater is installed, and may be of any preferred cross-sectional shape, as for instance the square form shown, having a door 2 constituting one of its sides for providing access into the interior of the heater whenever required. This door has a series of openings or louvers 3 therethrough for the admission of room air into the heater, and in this instance the air so admitted is entrained into the intake side of an air circulator or blower 5 that in turn feeds said air, after it has been heated, into the specific spaces intended to be heated. The bottom 41 of said outer casing may be of one or more sheets as shown.

The shells have mutually spaced-apart vertical bounding side walls, those of the inner shell being indicated at 66, while the front and rear walls of the outer shell. are indicated at 2 and 23, respectively, and there are transverse top walls 7 and 22, respectively, for said inner and outer shells. The Wall 7 closes across the top of the inner shell except for an opening 8 that is approximately centrally positioned, to form the combustion chamber 45 within said inner shell below the top wall 7, and there is a fuel burner device 9 mounted in said inner shell adjacent the bottom of the latter and communicating with said combustion chamber. Said inner shell has a fresh-air intake opening 10 through a transverse wall 42 across the shell slightly below afan 11 mounted in said shell in proximity to said burner and sufficiently close to said opening to aid in the entrainment of the air to feed said burner.

There is a tubular first flue 12 extending upwardly from the top of said combustion chamber, having its lowest end communicating with said opening 8, the peripheral bounding wall 13 of said flue extending upwardly through an opening 25 through the roof 14. This flue carries a cap 31 that extends radially outwardly from its upper end and there is a second cap 15 spaced vertically above the first cap to provide a laterally outwardly directed outlet opening or discharge passage 16 therebetween for the gases of combustion.

An upright side wall 17 is arranged between the rear Wall of the inner shell and the vertical rear wall 23 opposed thereto, said wall 17 being extended upwardly to slightly above the top of the combustion chamber, there being a top wall 18 extending transversely from the wall 17 as a closure except for said opening 8. Thus, said walls 17 and 18 constitute an inverted L-shaped partition between said shells as a seal to insure that none of the combustion gases enters the room being heated. A radiation shield 34 is interposed between said rear wall 6 and wall 17 and is coextensive with the latter. There is a vertical passageway 26 formed between said inner shell and shield 34, sealed across the top of the latter, and there is an opening 21 through the lower portion of said rear side wall of the inner shell, in open communication between said passageway 20 and the air intake side of the circulator 5.

Said circulator has its discharge end in the form of a pipe or conduit 35 that extends through registering openings 36 and 37 through the bottom of the shells and the room floor, respectively, the floor being indicated generally as 39, and there is an under-the-fioor duct system or plenum 40 leading from said conduit.

In order to provide sufficient draft for the burner, fresh air from the atmosphere is conducted through the heater to feed the burner, in a manner about to be described.

A transversely extending top wall 22 is arranged substantially parallel to and in spaced relation to said wall 18, the wall 22 being sealed completely from said flue although permitting the latter to pass vertically therethrough.

The vertical wall 17 extends upright in spaced relation to the rear wall 23 of the outer shell to closely adjacent the bottom of said shell, to provide a second upright passageway 24 to conduct atmospheric air to the burner, there being a lower air inlet opening 27 at the lower end of this passageway between the bottom of the shells and the wall 17, said passageway lower end being in open communication with said fresh-air intake 10.

A second flue 26 extends upwardly through said roof opening, spaced radially from the first flue, with its open upper end providing an upper air inlet 30 and with its lower open end communicating with the passageway 24, and there is an upright inner tubular wall 28 spaced laterally outwardly from said wall 13, said wall 28 having its lower end closed by a bottom wall 29 that is sealed against said flue wall 13. The upper terminal end of said wall 28 projects slightly above the corresponding uppermost end of the wall 26 and extends to near the cap 31 but slightly below the latter and open to said inlet 30. Said inlet 30 is only slightly below said outlet 16, the difference in elevation therebetween being in the nature of about four to six inches to permit of good operating efliciency without unduly heating the air going to the burner.

It is to be particularly noted that the hoods or caps are substantially alike in size and contour and are placed substantially closely one above the other, so that no matter what the wind effect is, the pressures created at the respective intake and discharge points are equal, thus maintaining the pressures across the burner constant and insuring a steady and constant volume of air for combustion under all wind conditions, and all without the use of extraneous devices such as a barometric draft regulator,. or. in the case of using a gas fuel, of a separate draft hood.

By locating the fresh air inlet 30 at approximately the same height as that of the place of gas discharge from the flue 12 into the atmosphere, the draft will be fairly well balanced to assure of substantially equal air pressures at the flue gas discharge and at the combustion air intake, to thereby result in a good operating efficiency of the heating system. Too little draft is objectionable, as the operating efliciency is lowered through failure to furnish enough air for properly burning the fuel. On the other hand, too much draft would tend to cause an over amount of carbon dioxide in the discharged flue gases on account of the air excess comingled with such flue gases, and this situation would result in a lowering of heater efliciency. The optimum is to use just suflicient air to be sure to get good heating results, but Without the necessity of heating too much air, and yet not overheat the flue gases, and this desired result is best obtained by properly balancing of draft to get substantially equal air pressures as hereinbefore noted.

In order to keep the temperature of the discharging flue gases properly low, a third flue is interposed between the first and second flues, somewhat as shown.

This third flue has its radially outermost wall, the previously mentioned tubular wall 28, sealed to the opposed annular wall of said first flue by said bottom wall 29, the upper end of said shell 28 extending slightly above the corresponding terminal end of the wall 2-6, so that said third flue too, is open to the atmosphere at said upper inlet 30. A tubular baffle 32 extends upright between said tubular walls 13 and 28, with its upper end terminating only slightly below the air discharge opening 16 of the first flue, the lower end of the baflle terminating only a slight distance above said sealing wall 29 and in turn sealed to said wall 13 thcreat, except for its opening 4-4 4 through the bottom .for admission of air from below said third flue and upwardly through the latter flue.

A transversely extending outwardly directed cap or dome 43 is carried at the top of said baflie 32, spaced slightly below the cap 31 and providing an air discharge space 33 to the atmosphere between the vertically spaced apart caps, the inner peripheral edge of the cap 43 being slightly spaced from the flue wall 13 throughout its height.

With such a construction, the atmospheric air upper inlet 30 serves for entrainment of air into the second and third flue in common, one portion of all of said entrained air therethrough going through said third flue traveling first downwardly along the radially outermost face of the baffle 32 to the bottom of the latter, and then reversing its direction of travel and upwardly through the openings 44 and along the inner face of said baffle, finally discharging into the atmosphere at 33. This last-mentioned portion of the air acts to cool the flue gases in the flue 12, to a substantially safe level to thereby avoid likelihood of overheating of the flue 12.

The second portion of atmospheric air entering through said common inlet 30 is entrained to travel downwardly between the annular walls 26 and 28, going downwardly through the passageway 24 and into the lower inlet 27 and finally upwardly through the fresh-air intake 10 to the burner.

In FIGURE 4, I have illustrated a modified form of construction, retaining all of the benefits and advantages of the flue structure hereinbefore set forth.

In said figure there are shown the outer and inner upright shells 2 and 4 as previously mentioned, with the inner or first flue communicating at its lower end with the interior of the combustion chamber 45 and with its upper terminal end discharging into the atmosphere.

Here too, the second or outer flue extends upwardly, spaced from the first flue and annularly encircling the latter and is so sealed to avoid possibility of leakage between said flues.

Caps, domes or cowls are carried at the upper terminal ends of said flues, the cowl 46 carried by said flue 12 and the cowl 47 carried at the corresponding end of the flue 26, both of said cowls projecting transversely or radially outwardly from their respective flues, as indicated.

In this instance, the cowls may be hollow, imperforate in their external or peripheral bounding walls 48 and 49, of the cowls 46 and 47, respectively, and with peripherally extending openings 50 and 51, respectively through their bottoms, so that said bottom openings provide the sole means of air entry into the throat of said cowls, or exit therethrough.

Here too, the cowls are positioned as close to the same elevation as is possible, taking into consideration the fact that the gases from the inner flue are heavier than air and will tend to fall toward the lower cowl and to become entrained into the latter, and re-circulated through the spaces in the rooms to be heated.

To minimize this tendency, the bounding peripheral wall of the lower cowl is flared radially outwardly as at 52 so that gases from the upper flue that impinge onto the lower cowl will tend to be deflected outwardly and away from the latter.

Both cowls have substantially the same peripheral size and contour so that the atmospheric air thereagainst will be maintained substantially equal at both of said throats.

I claim:

1. In a space heater to be placed in a room, inner and outer upright shells arranged one within the other and having vertical side walls and transverse top and bottom walls, each side and transverse wall of one shell being opposed to and spaced from the corresponding side and transverse wall of the other shell, said inner shell providing a combustion chamber therein, a fuel burner in the lower portion of said chamber, said inner shell having a fresh-air intake thereinto below said burner for leading fresh air to said burner, an upright side wall between a pair of said opposed vertical side walls and having its upper end terminating between the top walls of said shells and its lower end terminating below said fresh-air intake and above said bottom walls, a third top wall extending transversely from the top of said upright side wall to an opposed vertical side wall of said outer shell and together with the inner and outer shells forming a pair of sealedapart passageways one of which communicates with said fresh-air intake, an air circulator in the lower portion of said inner shell and sealed from said fresh-air intake and having an air intake opening through the inner shell vertical side wall that is adjacent and opposed to said upright side wall and is in communication with the other passageway and having a discharge pipe leading from said circulator through the bottoms of said shells, an upright inner flue having its lower end communicating with the upper end of said combustion chamber and its upper end discharging into the atmosphere, an upright outer flue enclosing and sealed from said inner flue and having its upper end communicating with said first passageway, said outer shell having a room-air inlet thereinto through one of its vertical side walls and that communicates through the other of the two sealed-apart passageways and to the air intake of said air circulator.

2. In a space heater adapted to be placed in a room, inner and outer shells arranged one within the other and spaced apart throughout their height, said shells having vertical side Walls and transverse top and bottom walls, the corresponding side walls and transverse walls of said shells being in opposed spaced relation to one another, said inner shell forming a combustion chamber therein with a fresh-air intake into said chamber adjacent its lower end, a fuel burner in the lower portion of said chamber, an upright side wall between a pair of said opposed vertical side walls and having its upper end terminating a spaced distance above the top wall of said inner shell and its bottom end above said bottom Walls, a top wall extending transversely from the top of said upright side wall to an opposed vertical side wall of said outer shell and together with the inner and outer shells forming a pair of sealedapart passageways one of which communicates with said fresh-air intake, an air circulator sealed from said fresh air intake and arranged in the lower portion of said inner shell and having an air intake through the inner shell side wall that is adjacent and opposed to said upright side wall and is in communication with the other passageway, said bottom walls having openings therethrough for discharging air from said circulator, an upright first ,flue having its lower end open to the upper end of said combustion chamber and having a discharge outlet at its upper end, an upright second flue enclosing and sealed from said first flue and having at its upper end a fresh-air inlet and communicating at its lower end with the upper end of said one passageway that communicates with said freshair intake, said outer shell having an inlet through one of its side walls for admission of room-air therethrough and that communicates through the other of the two sealed-apart passageways and to the air intake of said air circulator intake, and a third flue between said first and second flues and having a lower end sealed to said first flue, a tubular baffle upright between said first and third fines and extending upwardly from near the lower end of said third flue to near the upper end of said first flue, said third flue having an air inlet in common with said fresh-air inlet to thereby entrain through said third flue only a portion of all air that passes through said fresh-air inlet and having an outlet intermediate said discharge outlet of said first flue and said common inlet, whereby said air entrained into said third flue travels downwardly along one side of said baflie and thence upwardly along the other side of the same to discharge into the atmosphere through said last-mentioned outlet, said common inlet being at approximately the same elevation as the air discharge outlet of said first flue.

3. In a space heater, an annular upright shell having a combustion chamber therein that has a fresh-air intake thereinto adjacent its lower end, a fuel burner in said chamber receiving its air through said fresh-air intake, an upright first flue having its lower end open to the upper end of said chamber and discharging into the atmosphere through a discharge outlet at its upper end, an upright second flue annularly encircling and sealed from said first flue and having a fresh-air inlet at its upper end relatively closely adjacent the level of the discharge outlet of the first flue and leading downwardly to communicate with said fresh-air intake, and a third flue spaced between said first and second flues and having its upper end provided with an atmospheric air inlet communicating with said fresh-air inlet to be a common air inlet therewith, an upright baffle between said first and second flues and extending from the lower end of the latter to near the upper end of the first flue, said second flue having its lower end sealed to said first flue and open at its lower end, whereby said third flue entrains therethrough only a portion of all air taken through said common inlet and having a discharge outlet into the atmosphere intermediate said discharge outlet of said first flue and said common inlet.

4. In a space heater, an annular upright shell having a combustion chamber therein that has a fresh-air intake thereinto adjacent its lower end, a fuel burner in said chamber receiving its combustion air through said intake, an upright first flue having its lower end communicating with the upper end of said chamber and having an outlet at its upper end for discharging flue gases of combustion into the atmosphere, an upright second flue annularly encircling and sealed from said first flue and having a freshair inlet at its upper end relatively closely adjacent the discharging end of said first flue and leading downwardly to communicate with said fresh-air intake, and a third upright flue spaced between said first and second flues and having at its upper end an air inlet in common with said fresh-air inlet so that different portions of all air entering said common inlet enters said second and third flues, said third flue having an outlet into the atmosphere intermediate said discharge outlet of the first flue and said common inlet, an upright baflie in the form of a tube between said first and third flues extending downwardly from said common inlet to short of the bottom of said third flue and open at its lower end, and a seal between the lower end of said third flue and first flue, whereby only that portion of air through said common inlet that is entrained into said third flue travels downwardly along one side of said baflle and thence upwardly along its other side and finally discharges into the atmosphere through said third flue.

5. In a space heater to be placed in a room, inner and outer upright shells arranged one within the other and having vertical side walls and transverse top and bottom walls, each side wall and transverse walls of one shell being opposed to and spaced from the corresponding side and transverse wall of the other shell, said inner shell providing a combustion chamber therein, a fuel burner in the lower portion of said chamber, said inner shell having a fresh-air intake thereinto adjacent said burner for leading fresh air to the latter, an upright side wall between a pair of said opposed vertical side walls and having its upper end terminating between the top walls of said shells and its lower end terminating below said fresh-air intake and above said bottom walls, a third top wall extending transversely from the top of said upright side wall to an opposed vertical side Wall of said outer shell and together with the inner and outer shells forming a pair of sealedapart passageways one of which communicates with said fresh-air intake, a discharge pipe through the bottoms of said shells and leading from the second of said passageways, an upright inner flue having its lower end communicating with the upper end of said combustion chamber and its upper end discharging into the atmosphere, an upright outer flue enclosing and sealed from said inner flue and having its upper end communicating with the atmosphere and its lower end communicating with said first passageway, said outer shell having a room-air inlet thereinto through one of its vertical side walls and that communicates through said second of said passageways to said discharge pipe.

6. In a space heater, an annular upright shell having a combustion chamber therein with a fresh-air intake thereinto adjacent its lower end, a fuel burner in said chamber receiving its air feed from said intake, an upright first flue having its lower end open to the upper end of said chamber and discharging into the atmosphere through a discharge outlet at its upper end, an upright second flue annularly encircling said first flue and having a fresh-air inlet at its upper end relatively closely adjacent the level of discharge from said first flue and leading downwardly to open into said fresh-air intake, and a third flue spaced between said first and second flues and having its upper end provided with an atmospheric air inlet communicating with said fresh-air inlet so as to be a common inlet therewith, an upright tubular bafile open at both ends and spaced between said first and second fiues and extending upwardly from below the upper end of the latter and with its upper end terminating near the upper end of said third flue, said second flue having a transverse lower end sealed to said first flue, whereby said second flue entrains therethrough only a portion of all air taken through said common inlet and some of said last-mentioned downwardly moving entrained air reverses its direction and passes upwardly through the lower end of said baflle and discharges into the atmosphere adjacent said common inlet.

7. In a space heater, an upright shell having a combus tion chamber therein with a fresh-air intake thereinto adjacent its lower end, a fuel burner in said chamber receiving its air feed from said intake, an upright first flue having its lower end open to the upper end of said chamber and discharging into the atmosphere through a discharge outlet at its upper end, an upright second flue encircling said first flue and having a fresh-air inlet to the atmosphere at its upper end relatively closely adjacent the level of the first flue discharge outlet and with its lower end connected to communicate with said fresh-air intake, and a pair of concentric spaced sleeve means upright between and concentric to said first and second flues, the inner sleeve means being open at both ends and with its upper end discharging into the atmosphere, and the other sleeve means having its upper end open and terminating below the upper end of said inner sleeve means to communicate with said fresh-air inlet and its lower end sealed to said first flue below the lower end of said inner sleeve means, whereby said spaced sleeve means conduct some of the entrained air downwardly and thence upwardly to cool the gases passing through said first flue before its discharge into the atmosphere.

8. A space heater as set forth in claim 7, further characterized in having the upper end of said inner sleeve means below the upper end of said first flue.

References Cited in the file of this patent UNITED STATES PATENTS 2,763,196 Singleton Sept. 18, 1956 2,764,972 Ryder Oct. 2, 1956 2,898,839 McKann Aug. 11, 1959 2,964,034 Nordholt et al Dec. 13, 1960 

1. IN A SPACE HEATER TO BE PLACED IN A ROOM, INNER AND OUTER UPRIGHT SHELLS ARRANGED ONE WITHIN THE OTHER AND HAVING VERTICAL SIDE WALLS AND TRANSVERSE TOP AND BOTTOM WALLS, EACH SIDE AND TRANSVERSE WALL OF ONE SHELL BEING OPPOSED TO AND SPACED FROM THE CORRESPONDING SIDE AND TRANSVERSE WALL OF THE OTHER SHELL, SAID INNER SHELL PROVIDING A COMBUSTION CHAMBER THEREIN, A FUEL BURNER IN THE LOWER PORTION OF SAID CHAMBER, SAID INNER SHELL HAVING A FRESH-AIR INTAKE THEREINTO BELOW SAID BURNER FOR LEADING FRESH AIR TO SAID BURNER, AN UPRIGHT SIDE WALL BETWEEN A PAIR OF SAID OPPOSED VERTICAL SIDE WALLS AND HAVING ITS UPPER END TERMINATING BETWEEN THE TOP WALLS OF SAID SHELLS AND ITS LOWER END TERMINATING BELOW SAID FRESH-AIR INTAKE AND ABOVE SAID BOTTOM WALLS, A THIRD TOP WALL EXTENDING TRANSVERSELY FROM THE TOP OF SAID UPRIGHT SIDE WALL TO AN OPPOSED VERTICAL SIDE WALL OF SAID OUTER SHELL AND TOGETHER WITH THE INNER AND OUTER SHELLS FORMING A PAIR OF SEALEDAPART PASSAGEWAYS ONE OF WHICH COMMUNICATES WITH SAID FRESH-AIR INTAKE, AN AIR CIRCULATOR IN THE LOWER PORTION OF SAID INNER SHELL AND SEALED FROM SAID FRESH-AIR INTAKE AND HAVING AN AIR INTAKE OPENING THROUGH THE INNER SHELL VERTICAL SIDE WALL THAT IS ADJACENT AND OPPOSED TO SAID UPRIGHT SIDE WALL AND IS IN COMMUNICATION WITH THE OTHER PASSAGEWAY AND HAVING A DISCHARGE PIPE LEADING FROM SAID CIRCULATOR THROUGH THE BOTTOMS OF SAID SHELLS, AN UPRIGHT INNER 